1. Field of the Invention
The present invention relates to a new gas burner, in particular, for use in a domestic cooker, which is provided with an improved burner crown.
2. Description of the Related Art
A gas burner is substantially formed by a bowl-shaped body, a toothed crown and an upper cap. The bowl-shaped body is associated with an injector through which the gas is supplied. The burner crown is provided on its circumference with a plurality of ports to let a gas-air mixture exit in a radial direction. The cap closes the burner top and defines the flame ports together with the burner crown.
This kind of gas burner has flame ports equidistant from each other and of two or more different sizes. Moreover, the flame ports could also be different in length and width in order to let the gas-air mixture leave the burner at a desired velocity, pressure, inclination and at a requested distribution along the burner circumference. Some burner ports also have the function of a pilot flame, and they guarantee flame stability when flow variations, for instance, due to changes of rate (maximum to minimum and vice-versa), and external air turbulence could disturb the flame.
The flame stability under different operative conditions is a serious problem for all kinds of gas burners.
A main drawback is the flame breakdown from the burner cap, which occurs both in longitudinal and circular directions during the normal functioning of the burner. At present, a technical solution to reduce this danger is represented by a cap whose diameter is larger than that of the burner crown and, in particular, larger than the diameter of the flame port circumference.
This solution is not satisfactory from a technical point of view. In fact, the flame stability is also a function of the burning velocity of the gas-air mixture. By increasing the quantity of air in the mixture, the quality of the combustion is improved, but the burning velocity also increases; consequently, the flame stability decreases and approaches the flame lift limit. An enlarged diameter of the burner cap does not remove this drawback.
In addition, a cap larger than the burner crown is not a better solution from an aesthetic point of view.